THANK YOU. I'm currently writing a manual for a DAW and was baffled by the FM in a synth in it because I've pretty much only had experience with linear FM and had absolutely no idea what it was doing. It is INSANE that I've never heard of this distinction in FM types before. There seems to be shockingly little discussion about it online.
I’ve often wondered why the FM mode of my analogue synth doesn’t sound the same as even a 2-op patch, you’ve made it super clear! Also wow, people weren’t kidding when they said simply changing which operators are audible takes a few minutes in a traditional DX synth - in my Opsix I would’ve slid the faders for those operators down in two seconds! Of course I’d read it was an easier and faster user interface but I hadn’t looked into just how much that is true. Thanks!
i love this guy, he looks like he stole all the infinity stones. Thankfully some people are geeks on this subject and they give us "big guns" like he say. thanks for the video, very interesting.
I knew there was a difference between linear and exponential FM but, honestly, only because everyone talked about it. And of course I could hear the difference between "analog FM" and "digital FM". But never really understood the concept. Now I do, thank you for making this vid and compliments for your great explanation!
This synthesis method was also used in some arcade, console and PC videogames in form of the YM2151, YM2612 or YM3812 yamaha sound chips used during 80s and 90s. They bring me such good memories of my childhood...
at last i understand FM! ive been patching my moog dfam's pitch envelope into my mother-32's linear fm input to create a pseudo sidechain effect - whenever a kick drum hits, the frequency of the mother 32 (for example in a bassline) bends upwards a little depending on how much of the envelope i let through. it gets even better when putting the envelope through an inverter so that the linear fm causes the frequency to bend downwards, out of audible range. thank you for this great video. i look forward to more of your videos.
For someone studying eurorack modular synthesis this is a very nice inspiring video. Be it someone just starting or as a reminder review of a seasoned person. Thank you.
Keith! Excellent vid thank you! I'm a DSI Pro 2 owner and just found out about the Linear FM update for the Pro 2 firmware and I needed to know what the hell that even meant!
Thank you so much for that explanation! Realised i've been going about it all wrong trying to build fm in puredata and applied this theory and its sounds worlds beyond now! BRILLIANT!
That was very well explained, thank you! Could you shed some light on through-zero FM? What it is, how to achieve it and how it sounds different from regular linear FM?
Basically linear but you can crank the fm depth all the way without it sounding as gritty as normal linear fm. As the name suggests it allows to go beyond 0 (negative frequencies).
Great video - the DX7 actually uses Phase Modulation (PM) because it has a carrier wave that is used to alter the phase angle between them. Although PM is an intermediate step of achieving FM, FM is probably more just a marketing term by Yamaha. Either PM or FM are really just special cases of quadrature amplitude modulation (QAM) (mathematically speaking). I often joke by asking people how their QAM synth is going - you get some funny looks :) Keep it up - maybe do a video on Ring Modulators .... this is right up the same alleyway!
FM is frequency modulation, AM of course is amplitude modulation. These are not the same, and do not sound the same. You'll have to do some explaining to show how a quadrature generator is the same as phase modulation.
Doug Brown I didn't say they were the same not did I say that FM was AM. I said mathematically they (PM and FM) are special cases of QAM. more info here: en.m.wikipedia.org/wiki/Phase_modulation
I am sure phase modulation is a reasonable way to explain DX7 style synthesis, because the equations clearly show that phase modulation is what's happening. I am not sure why they call FM a special case of QAM, but I am not disputing it - I just can't explain it :)
Instant frequency is the first derivative of instant phase, so when both carrier and modulating signal are sine waves, there is no difference between FM and PM, because they produce the same signal. And don't believe Wikipedia, QAM is not superset of FM and PM. QAM is a digital modulation scheme with sine carrier, while FM and PM are analog modulation schemes with any periodical carrier. What you meant as QAM is not modulation at all, it is just one of the ways to represent narrowband signals, in terms of complex envelope.
Drizzgit , while there's no really robust analog FM sound synthesizer, this is a a hardware limitation, not a conceptual mismatch. Analog VCOs that respond quickly enough to changes in control voltage are just impractical for musical equipment. However the _principal_ of frequency/phase modulation is analog. I.e. it discusses only waveforms and analog signals.
I'm glad you liked the video. I'm currently working on a new video, showing how to develop a bass FM patch, with all of the nitty gritty details explained.
Great video! you did a great job clarifying the differences between lin and exp FM. I haven't ever bothered to do too much in the way of FM, but I tried some on my modular. Unfortunately the analog oscillators weren't perfect enough to get sounds similar to what you got on the DX11. Got me tempted to pick up a similar keyboard just to explore more along the lines of FM. Unfortunately most FM synths seem to have poor interfaces.
Opsix is the way to go if you want the structure of FM reflected in the user interface with almost one knob per function. The refaceDX someone else mentioned was certainly very good when it was new but compared to the Opsix there’s a lot more menu diving. Plus it’s just touch pads instead of knobs and faders.
Thanks this was really informative. The sound at the beginning of the video was a bit odd for me, but the explanation was crystal clear. Thanks again!!...
Some people say, Yamaha's FM synthesis is not really FM, but Phase Modulation, which I don't really get because frequency modulation is achieved by speeding and slowing (or even reversing backwards) a phase of a wave (I guess). So many things still to learn about my TX81z, but meanwhile I understood one thing. I need to learn about various natural (physical) ways harmonics "grow" from musical instruments too. E.g.: string instruments produce harmonics that are slightly sharper (therefore inharmonious) than basic note fq (thickness of a string). I don't know if that can be reproduced with DX synths, and there are some softsynths that can do that, but I can tell it's very difficult to find analytic texts about where in nature (I mean in physical systems like musical instruments, primarly) a frequency modulation occures, ...and how (and the ones that can be mimicked by FM, like cutoff filter sweeps)
Thanks for the video Keith, but I was thinking there might be more to digital FM, at least the way it is implemented by Yamaha. Isn't there something called 'through zero' FM that causes the harmonic series to be more 'manageable' in digital FM? Through zero FM is supposed to be a huge reason why FM synths sound the way they do. I know through zero can be implemented in analog but it's quite complicated. I'd love to see a video discussing more of this topic.
Yes. Yamaha-style FM synths do through zero as well, which is another thing that helps keep the carrier average frequency the same. The last thing is that Yamaha-style FM uses phase modulation instead of directly modulating frequency... the effect is mostly the same if your modulator is a sine wave, except it makes it much easier to keep the carrier in tune, since even if your modulator has a DC offset, the average frequency won't change.
This is the best explanation I've seen on FM so far! Could you explain how to use detune, course and fine? How does each frequency relate to the other operators? Currently I'm using the free VST Dexed (Yamaha DX7) but I'm not having much luck.
Great video, thanks, Keith! At around 6:50, you mention that Osc 4 in the vertical line algorithm oscillates itself. Could you please expand on that? I'm not sure I understand. Thanks again!
Hi Andrew. That's a great question! In linear FM, when an operator is in a feedback loop, the amplitude of the oscillator output will modulate the frequency of that same oscillator. In this case, as the amplitude of oscillator 4 increases, it will cause the pitch of oscillator 4 to go up. As the amplitude of oscillator 4 decreases, it will cause the pitch of oscillator 4 to go down. Since oscillator 4 is a sine wave (which has an amplitude that is constantly increasing and decreasing), it will cause the pitch of oscillator 4 to go up and down at the same rate. The overall amount of feedback is controlled by 3 things: the fixed output level of the operator, the feedback amount, and an amplitude envelope that is applied to the operator.
I'm quite confused about some videos that sate that FM synthesis is truly Phase modulation. So I'm not sure if they are wrong and it is just a problem fo confusing Linear and Exponential FM
Thanks for a clear and informative video! One question: was the pitch of oscillator 2 (the modulator) fixed? I think that was your point in contrasting exponential (modulator’s pitch tracks the keyboard) with linear (modulator’s pitch is constant, no matter what note you play?) Regrettably, I don’t have my DX 7 anymore, so I can’t check it out that easily! Thanks again.
Thanks, clear explanation,. Been playing with my software modular synth, in a few minutes got to understand much better what I'm doing.... shit, need to go to bed, but wnat to start building.....
![Alternate Tunings With The [KRM-100] MIDI-CV-Arpeggiator](http://i.ytimg.com/vi/yzl2V2ym-fQ/mqdefault.jpg)
![Alternate Tunings With The [KRM-100] MIDI-CV-Arpeggiator](/img/tr.png)
THANK YOU. I'm currently writing a manual for a DAW and was baffled by the FM in a synth in it because I've pretty much only had experience with linear FM and had absolutely no idea what it was doing. It is INSANE that I've never heard of this distinction in FM types before. There seems to be shockingly little discussion about it online.
You are most welcome. I'm glad you found my video useful.
I’ve often wondered why the FM mode of my analogue synth doesn’t sound the same as even a 2-op patch, you’ve made it super clear!
Also wow, people weren’t kidding when they said simply changing which operators are audible takes a few minutes in a traditional DX synth - in my Opsix I would’ve slid the faders for those operators down in two seconds! Of course I’d read it was an easier and faster user interface but I hadn’t looked into just how much that is true.
Thanks!
Best explanation of this subject on the net. Big up Keith!
i love this guy, he looks like he stole all the infinity stones. Thankfully some people are geeks on this subject and they give us "big guns" like he say. thanks for the video, very interesting.
FM is so weird. Musically, technically, everything-ly. This was great. I hope you can do a video with a Digitone one day.
I knew there was a difference between linear and exponential FM but, honestly, only because everyone talked about it.
And of course I could hear the difference between "analog FM" and "digital FM". But never really understood the concept.
Now I do, thank you for making this vid and compliments for your great explanation!
This synthesis method was also used in some arcade, console and PC videogames in form of the YM2151, YM2612 or YM3812 yamaha sound chips used during 80s and 90s. They bring me such good memories of my childhood...
Explained sega genesis and CX16 music to me quite well! (Both had a PSG inside them and a PCM channel too)
Get famitracker and make your own chiptune tracks!
Это лучшее разъяснение из всех, какие я когда-либо встречал! Спасибо, Keith! 👍👍👍
Best explanation on exponential fm on RUclips. Tried many vids and struggled. Thanks so much!
at last i understand FM! ive been patching my moog dfam's pitch envelope into my mother-32's linear fm input to create a pseudo sidechain effect - whenever a kick drum hits, the frequency of the mother 32 (for example in a bassline) bends upwards a little depending on how much of the envelope i let through. it gets even better when putting the envelope through an inverter so that the linear fm causes the frequency to bend downwards, out of audible range. thank you for this great video. i look forward to more of your videos.
For someone studying eurorack modular synthesis this is a very nice inspiring video. Be it someone just starting or as a reminder review of a seasoned person. Thank you.
Thanks Chas. I'm glad you found this video inspiring.
Great video Keith! Keep up the good work!
Thanks for making this video. It was a great explanation of the difference between exponential and linear FM.
Just found u channel. Great stuff brother.
Keith! Excellent vid thank you! I'm a DSI Pro 2 owner and just found out about the Linear FM update for the Pro 2 firmware and I needed to know what the hell that even meant!
Best demonstration ever. I learned something. I love it.
I'm glad you got something out of it! Thanks.
so important to understand and demystify, you are a great communicator.
Thank you so much for that explanation! Realised i've been going about it all wrong trying to build fm in puredata and applied this theory and its sounds worlds beyond now! BRILLIANT!
I like the pace of your videos. Also, this one is very informative - thanks for posting it!
That was very well explained, thank you! Could you shed some light on through-zero FM? What it is, how to achieve it and how it sounds different from regular linear FM?
Basically linear but you can crank the fm depth all the way without it sounding as gritty as normal linear fm. As the name suggests it allows to go beyond 0 (negative frequencies).
Best video on FM synthesis ever. Thank you!
thanks for this knowledge..great vid..hope for more.
Amazing, very clear & no bs explanation... thanks!
This is a fantastic video, thank you! I followed along on the DX100. Interesting how the patch sounds different.
Thanks. Still not sure whether I want to tackle FM but you've definitely made it more approachable.
I'm glad I could add some clarity.
Thanks, Keith, that was really informative and answered the questions I had regarding the difference between the two types of FM.
Fantastic video. Such a simple and direct explanation. Thank you!
more instruction classes on fm please!!!!! basic string/pads etc - these are great videos!
SAME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Great video - the DX7 actually uses Phase Modulation (PM) because it has a carrier wave that is used to alter the phase angle between them. Although PM is an intermediate step of achieving FM, FM is probably more just a marketing term by Yamaha. Either PM or FM are really just special cases of quadrature amplitude modulation (QAM) (mathematically speaking). I often joke by asking people how their QAM synth is going - you get some funny looks :)
Keep it up - maybe do a video on Ring Modulators .... this is right up the same alleyway!
FM is frequency modulation, AM of course is amplitude modulation. These are not the same, and do not sound the same. You'll have to do some explaining to show how a quadrature generator is the same as phase modulation.
Doug Brown I didn't say they were the same not did I say that FM was AM. I said mathematically they (PM and FM) are special cases of QAM. more info here: en.m.wikipedia.org/wiki/Phase_modulation
I am sure phase modulation is a reasonable way to explain DX7 style synthesis, because the equations clearly show that phase modulation is what's happening. I am not sure why they call FM a special case of QAM, but I am not disputing it - I just can't explain it :)
Instant frequency is the first derivative of instant phase, so when both carrier and modulating signal are sine waves, there is no difference between FM and PM, because they produce the same signal. And don't believe Wikipedia, QAM is not superset of FM and PM. QAM is a digital modulation scheme with sine carrier, while FM and PM are analog modulation schemes with any periodical carrier. What you meant as QAM is not modulation at all, it is just one of the ways to represent narrowband signals, in terms of complex envelope.
Drizzgit , while there's no really robust analog FM sound synthesizer, this is a a hardware limitation, not a conceptual mismatch. Analog VCOs that respond quickly enough to changes in control voltage are just impractical for musical equipment.
However the _principal_ of frequency/phase modulation is analog. I.e. it discusses only waveforms and analog signals.
I would have to agree with the Lumberjack man
Very clear explanations - thank you. Very well designed video.
I just bought a Yamaha TX-802, and I'd love to watch more videos like this to explain FM synthesis. Thank you! This was really great.
I'm glad you liked the video. I'm currently working on a new video, showing how to develop a bass FM patch, with all of the nitty gritty details explained.
Great!
Great video! you did a great job clarifying the differences between lin and exp FM. I haven't ever bothered to do too much in the way of FM, but I tried some on my modular. Unfortunately the analog oscillators weren't perfect enough to get sounds similar to what you got on the DX11. Got me tempted to pick up a similar keyboard just to explore more along the lines of FM. Unfortunately most FM synths seem to have poor interfaces.
you should check out yamaha's DX-Reface, it's got a good user interface with 4 operators
Cylonix Shapeshifter from intelijel is a beast of an FM complex osc as is Endorphines Furthrrrr generator.
Opsix is the way to go if you want the structure of FM reflected in the user interface with almost one knob per function.
The refaceDX someone else mentioned was certainly very good when it was new but compared to the Opsix there’s a lot more menu diving. Plus it’s just touch pads instead of knobs and faders.
I really appreciate your FM videos.
Your level of knowledge is a very enviable thing. I can’t wait to watch more!!
Thanks for the comment Grant.
This was very helpful for making identifying FM types!
You are welcome, Preston.
Awesome fm sound effects are alway's complex to make but worth it.
Amazingly clear and logic explanation. Best, by far. Congratulations, keep on creating amazing content!
Thanks for the compliment Corneliu.
Very interesting. Thanks for this easy to follow and understand video.
This actually made things clearer. Thanks.
No nonsense. Seriously wholesome.
Great!
I've always wondered what the difference was !!
Thanks mate :)
Best you tube video I've seen in ages. Thanks :) great explanation. The mist has cleared.
FM synthesis tutorial, preparing for Volca FM (feat. Nord Modular G2)
wonderful video and extremely clear explanation, thank you ☺️
Great explanation and demonstration. I hit subscribe about a minute and a half in. Checking out your other videos now.
Thanks for the subscribe Troy!
Great video! Looking forward to more hands on exporation on fm synthesis.
Underrated video man. Great job, liked!
Thank you!
Fascinating. Brilliantly explained.
easy to follow, very informative
Thanks this was really informative.
The sound at the beginning of the video was a bit odd for me, but the explanation was crystal clear. Thanks again!!...
excellent concepts thanks for this
Great video, Keith. Keep these coming !
You are an awesome teacher!
Very lightning explanation man. Thank You!
Well explained and informative video
Thanks Vitor, I'm glad to pass on what I know.
Some people say, Yamaha's FM synthesis is not really FM, but Phase Modulation, which I don't really get because frequency modulation is achieved by speeding and slowing (or even reversing backwards) a phase of a wave (I guess).
So many things still to learn about my TX81z, but meanwhile I understood one thing. I need to learn about various natural (physical) ways harmonics "grow" from musical instruments too. E.g.: string instruments produce harmonics that are slightly sharper (therefore inharmonious) than basic note fq (thickness of a string).
I don't know if that can be reproduced with DX synths, and there are some softsynths that can do that, but I can tell it's very difficult to find analytic texts about where in nature (I mean in physical systems like musical instruments, primarly) a frequency modulation occures, ...and how (and the ones that can be mimicked by FM, like cutoff filter sweeps)
simply Wonderful
Thank you. Great video :) Made perfect sense. Knowledge increased ✔
Hey! The Edirol UA-25! Nice to see one more around
Great vid I've been looking to find. Could you plz post other vids to explain other types of algorithms?
Nice explanation, thanks 👍
Nice job man, thank you for the video
Hey thanks man, this is very clear ...
This video topic/title is why I just sent a Subscription to your Channel ;)
Thank you Reso Factor!
Thanks for the video Keith, but I was thinking there might be more to digital FM, at least the way it is implemented by Yamaha. Isn't there something called 'through zero' FM that causes the harmonic series to be more 'manageable' in digital FM? Through zero FM is supposed to be a huge reason why FM synths sound the way they do. I know through zero can be implemented in analog but it's quite complicated. I'd love to see a video discussing more of this topic.
Yes. Yamaha-style FM synths do through zero as well, which is another thing that helps keep the carrier average frequency the same. The last thing is that Yamaha-style FM uses phase modulation instead of directly modulating frequency... the effect is mostly the same if your modulator is a sine wave, except it makes it much easier to keep the carrier in tune, since even if your modulator has a DC offset, the average frequency won't change.
Thanks so much for your reply. It was very informative.
Very helpful explanation, thanks.
Great explanation. Thanks!
Ok , got it ! Now going back to my DX7 ll with Grey Matter E ! Thanks .
Thank you very much Keith
great explanation, thanks keith!
Thanks a bunch! Great Video!
Well explained 👍
Thanks Keith,
Great video
This is the best explanation I've seen on FM so far!
Could you explain how to use detune, course and fine? How does each frequency relate to the other operators?
Currently I'm using the free VST Dexed (Yamaha DX7) but I'm not having much luck.
Great explanation.
thank you a lot, very informative video
great explanation! Thanks.
awesome vid Keith
Great video!
great video(s).
Great video, Thank you!
Thanks so much, this video was awesome!
Damn, was hoping someone could explain layer 3 and 4 in FM :)
LOVED IT
well done, I have a signed FM synthesis paper from John Chowning :)
Great video, thanks, Keith! At around 6:50, you mention that Osc 4 in the vertical line algorithm oscillates itself. Could you please expand on that? I'm not sure I understand. Thanks again!
Hi Andrew. That's a great question! In linear FM, when an operator is in a feedback loop, the amplitude of the oscillator output will modulate the frequency of that same oscillator. In this case, as the amplitude of oscillator 4 increases, it will cause the pitch of oscillator 4 to go up. As the amplitude of oscillator 4 decreases, it will cause the pitch of oscillator 4 to go down. Since oscillator 4 is a sine wave (which has an amplitude that is constantly increasing and decreasing), it will cause the pitch of oscillator 4 to go up and down at the same rate.
The overall amount of feedback is controlled by 3 things: the fixed output level of the operator, the feedback amount, and an amplitude envelope that is applied to the operator.
Thank you. Just, Thank you.
I'm quite confused about some videos that sate that FM synthesis is truly Phase modulation. So I'm not sure if they are wrong and it is just a problem fo confusing Linear and Exponential FM
Hey thank you for the information, i cleared my doubts respect this theme.
Thanks for the kind words Sir William.
Excellent. Thanks!
Great Job
Thanks for a clear and informative video!
One question: was the pitch of oscillator 2 (the modulator) fixed? I think that was your point in contrasting exponential (modulator’s pitch tracks the keyboard) with linear (modulator’s pitch is constant, no matter what note you play?)
Regrettably, I don’t have my DX 7 anymore, so I can’t check it out that easily!
Thanks again.
i think its the other way around
thanks, very clear and informative!
Finally, I get it!! Thank you
You are welcome.
Thanks, clear explanation,. Been playing with my software modular synth, in a few minutes got to understand much better what I'm doing.... shit, need to go to bed, but wnat to start building.....
Very useful. Thank you.
Awesome vid, thx
aweasome thanks
So : for simplify :
Exponential is modulation in term of pitch
Linear is modulation in term of Hertz
I finally have the response ! Thanks !